Thermal Physics

Question 1

How is the speed of particles in a body distributed?

Answer 1

Randomly

Question 2

How does the varying speed of particles in a body affect the kinetic energy?

Answer 2

Kinetic energy is distributed randomly

Question 3

How is the average kinetic energy of the particles affected by the temperature?

Answer 3

Higher temperature leads to higher average kinetic energy

Question 4

What is the internal energy of a body?

Answer 4

The sum of the randomly-distributed kinetic and potential energies of all its particles

Question 5

What is a system?

Answer 5

A group of bodies considered as a whole

Question 6

What is a closed system?

Answer 6

One that doesn’t allow any transfer of matter in or out

Question 7

How does the internal energy of a system change if it’s not heated and no work is done?

Answer 7

Constant

Question 8

How is energy constantly transferred between particles in a system?

Answer 8

Collisions between particles

Question 9

How can the internal energy of a system be changed?

Answer 9

By heating it

By doing work (changing its shape)

Question 10

Does the internal energy of a substance change when it undergoes a change in state?

Answer 10

Yes, it changes

Question 11

Does the kinetic energy of a substance change when it undergoes a change in state?

Answer 11

No, it doesn’t change

Question 12

Does the potential energy of a substance change when it undergoes a change in state?

Answer 12

Yes, it changes

Question 13

When happens to the potential energy and temperature when a liquid changes to a gas?

Answer 13

The potential energy increases but the temperature stays the same

Question 14

Define specific heat capacity

Answer 14

The amount of energy needed to raise the temperature of 1kg of the substance by 1K.

Question 15

What apparatus can be used to find the specific heat capacity?

Answer 15

Continuous-Flow Calorimeter

Question 16

Describe a Continuous-Flow Calorimeter

Answer 16

A steady rate of water flowing over a heating element, with two thermometers to measure temperature difference

Question 17

Define specific latent heat (of fusion/vaporisation)

Answer 17

The amount of thermal energy required to change the state of 1kg of a substance

Question 18

What is Boyle’s Law?

Answer 18

(At a constant temperature) the pressure and volume of a gas are inversely proportional

Question 19

What is Charles’ Law?

Answer 19

(At a constant pressure) the volume of a gas is directly proportional to its temperature (K)

Question 20

What is the Pressure Law?

Answer 20

(At a constant volume) the pressure of a gas is directly proportional to its temperature (K)

Question 21

What is the molecular mass?

Answer 21

The mass of one molecule of that gas

Question 22

What is molecular mass relative to?

Answer 22

The mass of a carbon-12 atom

Question 23

What is the molar mass of a substance?

Answer 23

The mass that one mole of that substance would have

Question 24

What is the Ideal Gas Equation?

Answer 24

(pV)/T = constant

Question 25

What is the constant in the Ideal Gas Equation equal to?

Answer 25

number of moles × molar gas constant (nR)

Question 26

what is the equation for work done in changing the volume of a gas at a constant pressure?

Answer 26

work done = pΔV

Question 27

What is Newton's Second Law?

Answer 27

Force equals the rate of change of momentum

Question 28

How do you calculate the mean square speed of a particle?

Answer 28

The average of the [squared speeds] of all the particles

Question 29

What is pressure equal to?

Answer 29

Force ÷ area

Question 30

What are the Simplifying Assumptions used in Kinetic Theory?

Answer 30

``` Molecules move randomly Molecules follow Newton's Laws Molecules move in straight lines Collisions a perfectly elastic Collision forces act much shorter than the time between them ```

Question 31

What do you call a gas that follows the Simplifying Assumptions in Kinetic Theory?

Answer 31

Ideal Gas

Question 32

What temperature (C) is Absolute Zero?

Answer 32

-273

Question 33

Are the Gas Laws empirical or theoretical?

Answer 33

Empirical

Question 34

Is Kinetic Theory empirical or theoretical?

Answer 34

Theoretical

Question 35

Describe Brownian motion

Answer 35

Particles suspended in a fluid move with a "zig-zag", random motion, due to collisions with fast, randomly-moving particles

Question 36

Give an example of Brownian motion

Answer 36

Smoke in air

Question 37

What is the random motion of smoke in air evidence of?

Answer 37

That the air is made up of tiny particles (atoms or molecules) moving quickly

Question 38

For which law is the pressure and volume of a gas inversely proportional?

Answer 38

Boyle's Law

Question 39

For which law is the volume of a gas directly proportional to its temperature (K)?

Answer 39

Charles' Law

Question 40

For which law is the pressure of a gas directly proportional to its temperature (K)?

Answer 40

Pressure Law